Are Polyester Cores Safe?Updated 5 months ago

YOKU Cores are made from medical-grade polyester.

While not all polyester is suitable for this purpose, the medical-grade polyester used in our Cores is designed to withstand saturation without deteriorating, provided the Core is used as directed (i.e., only once per Core and not re-applied with essential oils).

We have thoroughly researched organic cotton alternatives but found them neither sustainable nor safe for this application. Cotton, when repeatedly saturated, can lose its integrity and start to flake, potentially leading to inhalation of cotton fibers, which is not ideal. Additionally, many suppliers bleach organic cotton, making it unsafe for use with essential oils.